Something else is most accurate although not too far removed
It is a Lancia Beta Montecarlo (sold as a Lancia Scorpion in the USA).
The underlying chassis is similar in design and it uses the same basic suspension. The engine is instead the 2 litre 8v twincam that the X1/9 was originally destined to receive. Somewhat rarer that an X1/9, slightly more expensive (originally) and badly prone to rust due to low grade steel from Poland that was left rotting on the docks before it go to Fiat/Lancia.
Later models were much sturdier and the one you've found appears to be near immaculate (hard to tell from just photos of course). Not sure they are both the same car though - one is on alloy wheels, the other on steel wheels...